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Date: Mon, 29 Dec 2008 12:31:32 +0100
From: Ingo Molnar <mingo@...e.hu>
To: Herbert Xu <herbert@...dor.apana.org.au>
Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>,
"Tantilov, Emil S" <emil.s.tantilov@...el.com>,
"Kirsher, Jeffrey T" <jeffrey.t.kirsher@...el.com>,
netdev <netdev@...r.kernel.org>,
David Miller <davem@...emloft.net>,
"Waskiewicz Jr, Peter P" <peter.p.waskiewicz.jr@...el.com>,
"Duyck, Alexander H" <alexander.h.duyck@...el.com>,
Eric Dumazet <dada1@...mosbay.com>
Subject: Re: unsafe locks seen with netperf on net-2.6.29 tree
* Ingo Molnar <mingo@...e.hu> wrote:
> * Herbert Xu <herbert@...dor.apana.org.au> wrote:
>
> > On Mon, Dec 29, 2008 at 09:31:54PM +1100, Herbert Xu wrote:
> > >
> > > You also need to patch the other places where we use that percpu
> > > counter from process context, e.g., for /proc/net/tcp.
> >
> > In fact, it looks like just about every spot in the original
> > changeset (dd24c00191d5e4a1ae896aafe33c6b8095ab4bd1) may be run
> > from process context. So you might be better off making BH-disabling
> > variants of the percpu counter ops.
>
> i got the splat further below with Peter's workaround applied.
so i'm trying the (partly manual) temporary revert below. The deadlock
warning triggers very frequently so it masks a lot of other potential
problems so i needed some quick solution. Can test any other patch as
well.
Ingo
--------------->
>From 71b9aceb2b5a1d0e4c6ed5ad0967f45184b6d2f8 Mon Sep 17 00:00:00 2001
From: Ingo Molnar <mingo@...e.hu>
Date: Mon, 29 Dec 2008 12:27:09 +0100
Subject: [PATCH] Revert "net: Use a percpu_counter for orphan_count"
This reverts commit dd24c00191d5e4a1ae896aafe33c6b8095ab4bd1.
Conflicts:
net/ipv4/inet_connection_sock.c
Lockdep splat as per:
http://lkml.org/lkml/2008/12/29/50
---
include/net/sock.h | 2 +-
include/net/tcp.h | 2 +-
net/dccp/dccp.h | 2 +-
net/dccp/proto.c | 16 ++++++----------
net/ipv4/inet_connection_sock.c | 4 ++--
net/ipv4/proc.c | 2 +-
net/ipv4/tcp.c | 12 +++++-------
net/ipv4/tcp_timer.c | 2 +-
8 files changed, 18 insertions(+), 24 deletions(-)
diff --git a/include/net/sock.h b/include/net/sock.h
index 5a3a151..a2a3890 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -666,7 +666,7 @@ struct proto {
unsigned int obj_size;
int slab_flags;
- struct percpu_counter *orphan_count;
+ atomic_t *orphan_count;
struct request_sock_ops *rsk_prot;
struct timewait_sock_ops *twsk_prot;
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 218235d..a64e5da 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -46,7 +46,7 @@
extern struct inet_hashinfo tcp_hashinfo;
-extern struct percpu_counter tcp_orphan_count;
+extern atomic_t tcp_orphan_count;
extern void tcp_time_wait(struct sock *sk, int state, int timeo);
#define MAX_TCP_HEADER (128 + MAX_HEADER)
diff --git a/net/dccp/dccp.h b/net/dccp/dccp.h
index 0bc4c9a..3fd16e8 100644
--- a/net/dccp/dccp.h
+++ b/net/dccp/dccp.h
@@ -49,7 +49,7 @@ extern int dccp_debug;
extern struct inet_hashinfo dccp_hashinfo;
-extern struct percpu_counter dccp_orphan_count;
+extern atomic_t dccp_orphan_count;
extern void dccp_time_wait(struct sock *sk, int state, int timeo);
diff --git a/net/dccp/proto.c b/net/dccp/proto.c
index d5c2bac..959da85 100644
--- a/net/dccp/proto.c
+++ b/net/dccp/proto.c
@@ -40,7 +40,8 @@ DEFINE_SNMP_STAT(struct dccp_mib, dccp_statistics) __read_mostly;
EXPORT_SYMBOL_GPL(dccp_statistics);
-struct percpu_counter dccp_orphan_count;
+atomic_t dccp_orphan_count = ATOMIC_INIT(0);
+
EXPORT_SYMBOL_GPL(dccp_orphan_count);
struct inet_hashinfo dccp_hashinfo;
@@ -964,7 +965,7 @@ adjudge_to_death:
state = sk->sk_state;
sock_hold(sk);
sock_orphan(sk);
- percpu_counter_inc(sk->sk_prot->orphan_count);
+ atomic_inc(sk->sk_prot->orphan_count);
/*
* It is the last release_sock in its life. It will remove backlog.
@@ -1028,21 +1029,18 @@ static int __init dccp_init(void)
{
unsigned long goal;
int ehash_order, bhash_order, i;
- int rc;
+ int rc = -ENOBUFS;
BUILD_BUG_ON(sizeof(struct dccp_skb_cb) >
FIELD_SIZEOF(struct sk_buff, cb));
- rc = percpu_counter_init(&dccp_orphan_count, 0);
- if (rc)
- goto out;
- rc = -ENOBUFS;
+
inet_hashinfo_init(&dccp_hashinfo);
dccp_hashinfo.bind_bucket_cachep =
kmem_cache_create("dccp_bind_bucket",
sizeof(struct inet_bind_bucket), 0,
SLAB_HWCACHE_ALIGN, NULL);
if (!dccp_hashinfo.bind_bucket_cachep)
- goto out_free_percpu;
+ goto out;
/*
* Size and allocate the main established and bind bucket
@@ -1135,8 +1133,6 @@ out_free_dccp_ehash:
out_free_bind_bucket_cachep:
kmem_cache_destroy(dccp_hashinfo.bind_bucket_cachep);
dccp_hashinfo.bind_bucket_cachep = NULL;
-out_free_percpu:
- percpu_counter_destroy(&dccp_orphan_count);
goto out;
}
diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index c7cda1c..2ebfd9e 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -562,7 +562,7 @@ void inet_csk_destroy_sock(struct sock *sk)
sk_refcnt_debug_release(sk);
- percpu_counter_dec(sk->sk_prot->orphan_count);
+ atomic_dec(sk->sk_prot->orphan_count);
sock_put(sk);
}
@@ -633,7 +633,7 @@ void inet_csk_listen_stop(struct sock *sk)
acc_req = req->dl_next;
- percpu_counter_inc(sk->sk_prot->orphan_count);
+ atomic_inc(sk->sk_prot->orphan_count);
local_bh_disable();
bh_lock_sock(child);
diff --git a/net/ipv4/proc.c b/net/ipv4/proc.c
index 614958b..4944b47 100644
--- a/net/ipv4/proc.c
+++ b/net/ipv4/proc.c
@@ -54,7 +54,7 @@ static int sockstat_seq_show(struct seq_file *seq, void *v)
socket_seq_show(seq);
seq_printf(seq, "TCP: inuse %d orphan %d tw %d alloc %d mem %d\n",
sock_prot_inuse_get(net, &tcp_prot),
- (int)percpu_counter_sum_positive(&tcp_orphan_count),
+ atomic_read(&tcp_orphan_count),
tcp_death_row.tw_count,
(int)percpu_counter_sum_positive(&tcp_sockets_allocated),
atomic_read(&tcp_memory_allocated));
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 1f3d529..82b9425 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -277,7 +277,8 @@
int sysctl_tcp_fin_timeout __read_mostly = TCP_FIN_TIMEOUT;
-struct percpu_counter tcp_orphan_count;
+atomic_t tcp_orphan_count = ATOMIC_INIT(0);
+
EXPORT_SYMBOL_GPL(tcp_orphan_count);
int sysctl_tcp_mem[3] __read_mostly;
@@ -1836,7 +1837,7 @@ adjudge_to_death:
state = sk->sk_state;
sock_hold(sk);
sock_orphan(sk);
- percpu_counter_inc(sk->sk_prot->orphan_count);
+ atomic_inc(sk->sk_prot->orphan_count);
/* It is the last release_sock in its life. It will remove backlog. */
release_sock(sk);
@@ -1887,11 +1888,9 @@ adjudge_to_death:
}
}
if (sk->sk_state != TCP_CLOSE) {
- int orphan_count = percpu_counter_read_positive(
- sk->sk_prot->orphan_count);
-
sk_mem_reclaim(sk);
- if (tcp_too_many_orphans(sk, orphan_count)) {
+ if (tcp_too_many_orphans(sk,
+ atomic_read(sk->sk_prot->orphan_count))) {
if (net_ratelimit())
printk(KERN_INFO "TCP: too many of orphaned "
"sockets\n");
@@ -2790,7 +2789,6 @@ void __init tcp_init(void)
BUILD_BUG_ON(sizeof(struct tcp_skb_cb) > sizeof(skb->cb));
percpu_counter_init(&tcp_sockets_allocated, 0);
- percpu_counter_init(&tcp_orphan_count, 0);
tcp_hashinfo.bind_bucket_cachep =
kmem_cache_create("tcp_bind_bucket",
sizeof(struct inet_bind_bucket), 0,
diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index 0170e91..076030c 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -65,7 +65,7 @@ static void tcp_write_err(struct sock *sk)
static int tcp_out_of_resources(struct sock *sk, int do_reset)
{
struct tcp_sock *tp = tcp_sk(sk);
- int orphans = percpu_counter_read_positive(&tcp_orphan_count);
+ int orphans = atomic_read(&tcp_orphan_count);
/* If peer does not open window for long time, or did not transmit
* anything for long time, penalize it. */
--
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